# DeployTimeSubstitutedFile

`DeployTimeSubstitutedFile` is an extension of `BucketDeployment` that allows users to upload individual files and specify to make substitutions in the file.

Extends: Construct › BucketDeployment › DeployTimeSubstitutedFile
Implements: IConstruct, IDependable

- Source: [`aws-s3-deployment/lib/bucket-deployment.ts`](https://github.com/aws/aws-cdk/blob/v2.275.0/packages/aws-cdk-lib/aws-s3-deployment/lib/bucket-deployment.ts#L762)
- Type last changed: v2.269.0 · 10 Sep 2026

## Example

```ts
import * as lambda from 'aws-cdk-lib/aws-lambda';

declare const myLambdaFunction: lambda.Function;
declare const destinationBucket: s3.Bucket;
//(Optional) if provided, the resulting processed file would be uploaded to the destinationBucket under the destinationKey name.
declare const destinationKey: string;
declare const role: iam.Role;

new s3deploy.DeployTimeSubstitutedFile(this, 'MyFile', {
  source: 'my-file.yaml',
  destinationKey: destinationKey,
  destinationBucket: destinationBucket,
  substitutions: {
    variableName: myLambdaFunction.functionName,
  },
  role: role,
});
```

## Initializer

```ts
new DeployTimeSubstitutedFile(scope: Construct, id: string, props: DeployTimeSubstitutedFileProps)
```

## Construct Props

- `destinationBucket`: [IBucket](/cdk/api/v2/docs/aws-cdk-lib.aws_s3.IBucket.html) (required) — The S3 bucket to sync the contents of the zip file to.

- `destinationKey`: string — The object key in the destination bucket where the processed file would be written to.

  **Default:** Fingerprint of the file content would be used as object key

- `role`: [IRole](/cdk/api/v2/docs/aws-cdk-lib.aws_iam.IRole.html) — Execution role associated with this function.

  **Default:** A role is automatically created

- `source`: string (required) — Path to the user's local file.

- `substitutions`: { [key: string]: string } (required) — User-defined substitutions to make in the file.

  Placeholders in the user's local file must be specified with double curly
  brackets and spaces. For example, if you use the key 'xxxx' in the file,
  it must be written as: {{ xxxx }} to be recognized by the construct as a
  substitution.

## Properties

- `bucket`: [IBucket](/cdk/api/v2/docs/aws-cdk-lib.aws_s3.IBucket.html)

- `deployedBucket`: [IBucket](/cdk/api/v2/docs/aws-cdk-lib.aws_s3.IBucket.html) — The bucket after the deployment.

  If you want to reference the destination bucket in another construct and make sure the
  bucket deployment has happened before the next operation is started, pass the other construct
  a reference to `deployment.deployedBucket`.

  Note that this only returns an immutable reference to the destination bucket.
  If sequenced access to the original destination bucket is required, you may add a dependency
  on the bucket deployment instead: `otherResource.node.addDependency(deployment)`

- `handlerRole`: [IRole](/cdk/api/v2/docs/aws-cdk-lib.aws_iam.IRole.html) — Execution role of the Lambda function behind the custom CloudFormation resource of type `Custom::CDKBucketDeployment`.

- `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) — The tree node.

- `objectKey`: string

- `objectKeys`: string[] — The object keys for the sources deployed to the S3 bucket.

  This returns a list of tokenized object keys for source files that are deployed to the bucket.

  This can be useful when using `BucketDeployment` with `extract` set to `false` and you need to reference
  the object key that resides in the bucket for that zip source file somewhere else in your CDK
  application, such as in a CFN output.

  For example, use `Fn.select(0, myBucketDeployment.objectKeys)` to reference the object key of the
  first source file in your bucket deployment.

- `objectVersionIds`: string[] — `objectVersionIds` is not supported for `DeployTimeSubstitutedFile`, which always extracts its file (`extract` is forced to `true`), so there is no single deployed object to version.

- `PROPERTY_INJECTION_ID`: string (static) — Uniquely identifies this class.

## Methods

- `addSource(source: ISource): void` — Add an additional source to the bucket deployment.

  ```ts
  declare const websiteBucket: s3.IBucket;
  const deployment = new s3deploy.BucketDeployment(this, 'Deployment', {
    sources: [s3deploy.Source.asset('./website-dist')],
    destinationBucket: websiteBucket,
  });

  deployment.addSource(s3deploy.Source.asset('./another-asset'));
  ```

- `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct.

  Use this method instead of `instanceof` to properly detect `Construct`
  instances, even when the construct library is symlinked.

  Explanation: in JavaScript, multiple copies of the `constructs` library on
  disk are seen as independent, completely different libraries. As a
  consequence, the class `Construct` in each copy of the `constructs` library
  is seen as a different class, and an instance of one class will not test as
  `instanceof` the other class. `npm install` will not create installations
  like this, but users may manually symlink construct libraries together or
  use a monorepo tool: in those cases, multiple copies of the `constructs`
  library can be accidentally installed, and `instanceof` will behave
  unpredictably. It is safest to avoid using `instanceof`, and using
  this type-testing method instead.

  **Parameters**

  - `x` — Any object.

  **Returns:** true if `x` is an object created from a class which extends `Construct`.

- `toString(): string` — Returns a string representation of this construct.

- `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct.

  Mixins are applied in order. The list of constructs is captured at the
  start of the call, so constructs added by a mixin will not be visited.
  Use multiple `with()` calls if subsequent mixins should apply to added
  constructs.

  **Parameters**

  - `mixins` — The mixins to apply.

  **Returns:** This construct for chaining